scholarly journals Peculiarities in structure formation and corrosion of cast quasicrystalline Al63Cu25Fe12 and Al63Co24Cu13 alloys in sodium chloride aqueous solution

2020 ◽  
Vol 21 (3) ◽  
pp. 530-536
Author(s):  
O. V. Sukhova ◽  
V. A. Polonskyy
Keyword(s):  
Sodium Chloride ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
Corrosion Properties ◽  
Free Corrosion Potential ◽  
X Ray ◽  
Marine Climate ◽  
Potentiodynamic Method

In this work the structure and corrosion behavior of quasicrystalline cast Al63Cu25Fe12 and Al63Co24Cu13 alloys in 5-% sodium chloride solution (рН 6.9–7.1) were investigated. The alloys were cooled at 5 К/s. The structure of the samples was studied by methods of quantitative metallography, X-ray analysis, and scanning electron microscopy. Corrosion properties were determined by the potentiodynamic method. The made investigations confirm the formation of stable quasicrystalline icosahedral (y) and decagonal (D) phases in the structure of Al63Cu25Fe12 and Al63Co24Cu13 alloys correspondingly. In 5-% sodium chloride solution, the investigated alloys corrode under electrochemical mechanisms with oxygen depolarization. Compared with Al63Cu25Fe12 alloy, Al63Co24Cu13 alloy has a less negative value of free corrosion potential (–0.43 V and–0.66 V, respectively), and its electrochemical passivity region extends due to the inhibition of anodic processes. A corrosion current density, calculated from (E,lgi)-curve, for Al63Co24Cu13 alloy amounts to 0.18 mА/сm2 and for Al63Cu25Fe12 alloy – to 0.20 mА/сm2. The lower corrosion resistance of Al63Cu25Fe12 alloy may be explained by the presence of iron-containing phases in its structure. Based on obtained results, the Al63Co24Cu13 alloy was recommended as a coating material for rocket-and-space equipment working in a marine climate.

Influence of anodic coatings on stress corrosion behaviour of 7017 aluminium alloy

2013 ◽  
Vol 61 (1) ◽  
pp. 27-31 ◽  
Author(s):  
Panagiotis Spathis
Keyword(s):  
Sodium Chloride ◽  
Aluminium Alloy ◽  
Aluminium Alloys ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Corrosion Potential ◽  
Nacl Solution ◽  
Free Corrosion Potential ◽  
Content Type ◽  
Dry Air

Purpose – The purpose of this work was to study the cracking susceptibility of a 7017 aluminium alloy, after anodising under various conditions. Design/methodology/approach – Slow strain tests in dry air, laboratory air and sodium chloride solution were employed. Anodic oxide films were produced with various applied current densities and thicknesses, in horizontal or vertical orientation of the coatings, at the free corrosion potential and also at various anodic or cathodic potentials. For the interpretation of the results, a metallographic study of the specimens before and after straining to failure was carried out using a scanning electron microscope. Findings – The behaviour of anodic coatings was found to depend very much on the anodising conditions. The coatings reduced the ductility of the alloy in dry air but can actually increase the ductility in laboratory air and in 3.5 per cent sodium chloride solution. In most cases, the ductility of coated specimens was greater in 3.5 per cent NaCl solution than in dry air, possibly due to crack blunting by the aggressive environment. Anodic coatings moved the free corrosion potential of the alloy in the noble direction and both the anodised and the bare alloy generally suffered a reduction in ductility at potentials anodic or cathodic to the free corrosion potential, the fall being more rapid for the anodised alloy. Research limitations/implications – The mechanism causing the increased ductility of coated specimens in 3.5 per cent NaCl solution than in dry air remains yet to be confirmed. Practical implications – The selection of suitable anodic coatings for the protection of aluminium alloys against stress corrosion cracking depends on the anodising conditions. Originality/value – The paper provides information regarding the influence of anodising conditions on the anticorrosive properties of electrolytically prepared anodic coatings on aluminium alloys.

THE INHIBITION EFFECT OF ZINC AND SILICATE IONS ON PITTING CORROSION INDUCED BY CERIUM(III) IONS OF CARBON STEEL IN SODIUM CHLORIDE SOLUTION

2020 ◽  
pp. 2050038
Author(s):  
QIONGWEI LI
Keyword(s):  
Sodium Chloride ◽  
Carbon Steel ◽  
Pitting Corrosion ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Corrosion Potential ◽  
In Situ Observation ◽  
Inhibition Effect ◽  
Synergistic Inhibition

Pitting corrosion of carbon steel in sodium chloride solution induced by Ce[Formula: see text] and the synergistic inhibition effects of Ce[Formula: see text] and Zn[Formula: see text]/SiO[Formula: see text] were investigated using in-situ observation and electrochemical methods. The results showed that the presence of Ce[Formula: see text] could result in severe pitting corrosion and a positive shift in the corrosion potential. It was found that individual Ce[Formula: see text], Zn[Formula: see text], or SiO[Formula: see text] had low inhibition efficiencies, whereas the combination of Ce[Formula: see text] and Zn[Formula: see text] or SiO[Formula: see text] proved to be highly effective in inhibiting the development of pits in two different ways and in enhancing the corrosion resistance. The pitting corrosion and inhibition mechanisms were discussed based on the results.

Corrosion Resistance of High-Alloyed Material UNS N08028 in Sodium Chloride Solution

2014 ◽  
Vol 893 ◽  
pp. 440-443
Author(s):  
Li Na Zhang ◽  
Jerzy A. Szpunar ◽  
Jian Xin Dong ◽  
Mai Cang Zhang
Keyword(s):  
Corrosion Resistance ◽  
Sodium Chloride ◽  
Corrosion Rate ◽  
Current Density ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Corrosion Potential ◽  
Ph Value ◽  
Chloride Concentration ◽  
Decreasing Ph

The influence of ions chloride concentration and pH value on the corrosion resistance of high-alloyed material UNS N08028 in the sodium chloride solution is investigated. Results show that the corrosion potential is active cathodically with the increase of chloride concentration. The current density and corrosion rate both increase with increasing chloride concentration and decreasing pH value.

X-Ray Photoelectron Spectroscopic Study of the Oxide Film on an Aluminum-Tin Alloy in 3.5% Sodium Chloride Solution

CORROSION ◽  
1997 ◽  
Vol 53 (10) ◽  
pp. 808-812 ◽  
Author(s):  
A. Venugopal ◽  
P. Veluchamy ◽  
P. Selvam ◽  
H. Minoura ◽  
V. S. Raja
Keyword(s):  
Sodium Chloride ◽  
Oxide Film ◽  
Spectroscopic Study ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
X Ray

scholarly journals Structure And Corrosion of Quasicrystalline Cast Al–Co–Ni and Al–Fe–Ni Alloys in Aqueous NaCl Solution

2020 ◽  
Keyword(s):  
Sodium Chloride ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Saline Solution ◽  
Silver Chloride ◽  
Reference Electrode ◽  
Electrolytic Cell ◽  
Passive State ◽  
Corrosion Properties ◽  
Stationary Potential

In this work the structure and corrosion behavior of quasicrystalline cast Al69Co21Ni10 and Al72Fe15Ni13 alloys in 5-% sodium chloride solution (рН 6.9–7.1) were investigated. The alloys were cooled at 5 К/s. The structure of the samples was studied by methods of quantitative metallography, X-ray analysis, and scanning electron microscopy. Corrosion properties were determined by potentiodynamic method. Stationary potential values were measured by means of long-term registration of (Е,τ)–curves using ПІ–50–1 potentiostat and ПР–8 programmer with three-electrode electrolytic cell. A platinum electrode served as counter electrode and silver chloride – as reference electrode. The made investigations confirm the formation of stable quasicrystalline decagonal D-phase in the structure of Al69Co21Ni10 and Al72Fe15Ni13 alloys. In Al69Co21Ni10 alloy, at room temperature D-phase coexists with crystalline Al9(Co,Ni)2 phase, and in Al72Fe15Ni13 alloy – with Al5FeNi phase. Comparison of Vickers hardness of these phases exhibits the following sequence: H(D-AlCoNi)>H(D-AlFeNi)>H(Al5FeNi)>H(Al9(Co,Ni)2). In 5-% sodium chloride solution, the investigated alloys corrode under electrochemical mechanisms with oxygen depolarization. Compared with Al72Fe15Ni13 alloy, Al69Co21Ni10 alloy has more negative value of stationary potential (–0,40 V and –0,48 V, respectively), and its electrochemical passivity region extends due to the inhibition of anodic processes. For both alloys, transition to passive state in the saline solution is observed. A corrosion current density, calculated from (E,lgi)-curve, for Al69Co21Ni10 alloy amounts to 0.12 mА/сm2 and for Al72Fe15Ni13 alloy – to 0.14 mА/сm2. After immersion in the saline solution for 8 days, pits are revealed on the surface of the alloys in areas, mainly where the phase boundaries and flaws are located. The number and size of pits are smaller on the surface of Al69Co21Ni10 alloy as compared with those on the surface of Al72Fe15Ni13 alloy. The lower corrosion resistance of Al72Fe15Ni13 alloy may be explained by the presence of iron-containing phases in its structure. Based on obtained results, the Al69Co21Ni10 alloy has been recommended as coating material for rocket-and-space equipment working in marine climate.

The nature and cause of seaminess in Cheddar cheese

1965 ◽  
Vol 32 (1) ◽  
pp. 35-44 ◽  
Author(s):  
J. Conochie ◽  
B. J. Sutherland
Keyword(s):  
Sodium Chloride ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Cheddar Cheese ◽  
Calcium Orthophosphate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phosphate Ions ◽  
Calcium Phosphorus ◽  
Chemical Studies

SummaryMicroscopical and chemical studies of seaminess in Cheddar cheese revealed that the white lines or seams characteristic of the defect are sections through layers of crystals lying between the milled curd particles. The crystals were identified from their X-ray diffraction pattern and by their refractive index as calcium orthophosphate dihydrate, CaHPO4. 2H2O. On each side of the adjoining curd surfaces in affected cheese there is a zone about 20 μm thick of strongly contracted protein which is almost devoid of crystals.Adding sodium chloride to cheddared curd increased the quantities of calcium, phosphorus and water released. The increases were proportional to the amount of salt applied within the range 0–2·5 g NaCl per 100 g curd.The solubility of calcium orthophosphate was found to rise from about 0·0025 M in water to a maximum of 0·008M in 2 M sodium chloride solution.It is postulated that calcium and phosphate ions released from the curd into the seam crystallize in the form of CaHPO4. 2H2O as the solubility of the compound is lowered by diffusion of salt from the surfaces into the curd particles.

scholarly journals Influence of Seawater Salinity on Corrosion of Hull Structural Steel

2019 ◽  
Vol 26 (2) ◽  
pp. 189-195
Author(s):  
Paweł Zagożdżon ◽  
Robert Starosta
Keyword(s):  
Sodium Chloride ◽  
Structural Steel ◽  
Current Density ◽  
Mass Fraction ◽  
Corrosion Current Density ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
Corrosion Properties ◽  
Corrosion Tests ◽  
Seawater Salinity

Abstract Hulls of ships are often made of steel, which are produced under the supervision of classification societies. Usually, the hull steel of ordinary strength category A is used for the ship's shell (the yield strength is 235 MPa and the impact strength 27 J at 20ºC). Vessels sail in sea areas with various levels of salinity and thus with different corrosiveness. The average salinity of the seas is taken as 3.5% content of sodium chloride. This article presents the results of corrosion tests of S235 JRG1 steel in an aqueous solution in which the mass fraction of sodium chloride was: 0.7%, 1.4%, 2.2%, 2.8%, 3.5% and 4.2%. Corrosion tests were performed using the potentiodynamic method. As parameters characterizing the corrosion properties of the tested steel, the corrosion current density and corrosion potential were assumed. Statistically significant influence of seawater salinity on the corrosion properties of hull structural steel of ordinary strength of category A was found. The highest value of the corrosion current density was observed in the solution containing 3.5% NaCl mass fraction was observed. In seawater with a sodium chloride content in the range of 0.7 to 3.5%, an increase in the value of the corrosion current density was observed, along with the increasing share of NaCl. In seawater with higher salinity, the corrosion rate was reduced. The corrosion potential of S235JRG1 steel decreases with the NaCl content in the corrosive solution. The susceptibility of this material to corrosion in seawater increased.

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